In the past, fire proofing plastic involved embedding flame-retardant particles directly into the resin matrix. The technique is fine for materials which are not meant to bear load. However, the amount of flame-retardant particles needed to be effective in higher mass objects, for example plastic lumber, is too high. Disruption of the networks within a plastic significantly affects the strength and elastic modulus. Therefore, embedded particles are suitable for thinner products, for example casings for electronics and dash boards for cars. However, for structural applications of plastic a different approach must be considered to reduce the threat of fire.
Because fire is a surface phenomenon, coatings that sufficiently adjust a surface's characteristics in favor of fire resistance are important. Because the coating represents the only barrier between the plastic fuel and a possible fire source, it must remain effective throughout the fire; delaying ignition of the plastic; and hindering propagation.